1. Field of the Invention
Embodiments of the present invention relate to a processing apparatus, and more particularly, to a sputtering apparatus for processing a large-scale substrate, a method of operating the sputtering apparatus, and a method of manufacturing a substrate using the sputtering apparatus.
2. Description of the Related Art
A display panel, such as a liquid crystal display device (LCD) or a plasma display panel (PDP) is built upon a substrate through a plurality of processes, such as a deposition process and an etching process. Each of the processes is performed using a separate processing apparatus. Among the apparatuses, a sputtering apparatus for forming a thin film is essential for manufacturing the display panel.
FIG. 1 is a cross-sectional view of a sputtering apparatus according to the related art. Referring to FIG. 1, the sputtering apparatus includes a susceptor 2 and a plurality of target devices 4 that are disposed to face the susceptor 2. A substrate 1 to be processed is securely seated on the susceptor 2, and a predetermined positive voltage is supplied to the susceptor 2.
As shown in FIG. 1, the target devices 4 are arranged along a line in such a way that they face the susceptor 2 or the substrate 1 on the susceptor 2. The width “w2” of a gap between adjacent target devices 4 is very small so that target particles are uniformly deposited on the substrate 1. For example, the width “w2” f a gap between adjacent target devices 4 is much smaller than the width “w1” of each of the target devices 4.
Each target device 4 includes a target 5, a baking plate 6, and a magnet 7. Thus, the sputtering apparatus including a plurality of target devices 4 has a plurality of targets 5, a plurality of baking plates 6, and a plurality of magnets 7. A predetermined negative voltage is applied to each target 5, and target particles are emitted from each target 5 because of collisions between each target 5 and ions.
The target 5 is fixed on the front surface of the baking plate 6 that faces the susceptor 2. Each baking plate 6 supports the target 5 and dissipates heat from the target 5. The magnet 7 is disposed on the rear surface of the baking plate 6 such that the magnet 7 induces electrons to be collected to facilitate a plasma discharge in an internal space 8 between the target 5 and the susceptor 2. The space 8 between the target 5 and the susceptor 2 is filled with inert gas, such as Ar gas, for plasma discharge.
When a predetermined high voltage is applied between the susceptor 2 and the target 5 as a result of the predetermined negative voltage applied to each target 5 and the predetermined positive voltage supplied to the susceptor 2, the Ar gas in the space 8 between the target 5 and the susceptor 2 is ionized into Ar+ ions that form a plasma. Because more electrons are collected by the magnetic field of the magnet 7, the generated plasma can become high-density plasma. A region of the high-density plasma contains Ar+ ions. A predetermined potential difference occurs between the high-density plasma region and the target 5 supplied with the predetermined negative voltage. The Ar+ ions contained in the high-density plasma region are accelerated by the energy of the predetermined potential difference so as to collide against the target 5. These collisions cause the target 5 to emit target particles, and the emitted target particles are deposited on the substrate 1.
As the size of a substrate to be processed increases, the size of the sputtering apparatus for processing a substrate must also increase. In particular, the number of the target devices 4 increases as the size of the substrate 1 increases, thereby increasing costs of the sputtering apparatus. To uniformly deposit target particles out to an edge region of the substrate 1, the target devices 4 are provided such that the total distribution width d2 of the target devices 4 is greater than the width “d1” of the substrate 1. Thus, the size of the sputtering apparatus is actually greater than the size of the substrate 1.
The target devices 4 are affixed to an external wall or a support such that the target devices 4 do not move or rotate in any direction. Target particles emitted from each of the targets 5 are deposited on portions of the facing substrate 1 respectively facing each of the targets. FIG. 2 is a schematic cross-sectional view showing the propagation directions of target particles that are emitted from targets of the related art sputtering apparatus. As shown in FIG. 2, the target 5 is impacted by Ar+ ions located at the front of the target 5 such that target particles are emitted from the target 5 in a slightly spread distribution pattern and deposit on the facing substrate 1. Because of the slightly spread distribution pattern, target particles from adjacent targets 5 adjacent to each other can be deposited on the same portion of the substrate 1. Accordingly, as shown in FIG. 3, more target particles are deposited on first portions p1 of the substrate 1, which are directly opposite to boundary regions between adjacent targets 5, than on second regions p2 of the substrate 1, which are directly opposite to the targets 5. Consequently, a layer 9 formed on the substrate 1 from the target particles has an uneven surface. Such an uneven layer 9 has poor performance in terms of operational characteristics and image-quality characteristics.